The objective of this study is to investigate the relationship between DNA damage and exposure to carcinogens or mutagens in selected occupations. We will 1) study occupational groups exposed to known or suspected carcinogens and mutagens by determining the rates of chromosome aberrations (ChAbs) and sister chromatid exchanges (SCEs) in these groups (exposures include benzene, coke oven fume, acrylonitrile, and lead; 2) compare the sensitivity of SCEs to ChAb's by examining the rates of these two tests in 3 occupational exposures (arsenic, lead, benzene) which have been associated with elevated ChAbs. The rates of DNA damage for exposed groups and control groups from the same industry will be compared. Personal exposure will be determined by traditional air sampling techniques. Where multiple carcinogen exposures occur or where it is technically difficult to measure a suspected carcinogen, 2 new methods of estimating level of exposure will be used. Both are based on the Salmonella microsome (SM) test. In the 1st method, urine samples are concentrated and assayed for mutagenic activity. In the 2nd, air samples are fractionated and tested for mutagenic activity.